Objectives To assess the long-term effect of bariatric surgery on the incidence of gout and hyperuricaemia in participants of the Swedish Obese Subjects (SOS) study.
Methods This report includes 1982 subjects who underwent bariatric surgery and 1999 obese controls from the SOS study, a prospective intervention trial designed to assess the effect of bariatric surgery compared with conventional treatment. None of the subjects had gout at baseline. An endpoint on gout incidence was created based on information on gout diagnosis and use of gout medications through national registers and questionnaires. Median follow-up for the incidence of gout was about 19 years for both groups. Moreover, the incidence of hyperuricaemia over up to 20 years was examined in a subgroup of participants having baseline uric acid levels <6.8 mg/dL.
Results Bariatric surgery was associated with a reduced incidence of gout compared with usual care (adjusted HR 0.60, 95% CI 0.48 to 0.75, p<0.001). The difference in absolute risk between groups was 3 percentage points at 15 years, and the number of subjects needed to be treated by bariatric surgery to prevent one incident gout event was 32 (95% CI 22 to 59). The effect of bariatric surgery on gout incidence was not influenced by baseline risk factors, including body mass index. During follow-up, the surgery group had a lower incidence of hyperuricaemia (adjusted HR 0.47, 95% CI 0.39 to 0.58, p<0.001). The difference in absolute risk between groups was 12 percentage points at 15 years, and the number of participants needed to be treated by bariatric surgery to prevent hyperuricaemia was 8 (95% CI 6 to 13).
Conclusions Bariatric surgery prevents gout and hyperuricaemia in obese subjects.
Trial registration number NCT01479452; Results.
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Handling editor Tore K Kvien
Contributors CM contributed to the design of the study, performed the analyses, contributed to the interpretation of data and wrote the first draft of the manuscript; MP edited the analysis, helped with the interpretation of the data and revised the manuscript; MN contributed to the design of the study, edited and revised the manuscript; PJ edited and revised the manuscript; LJ contributed to the design of the study and the interpretation of data and revised the manuscript. AR and LMSC supervised the study, contributed to the design of the study and the interpretation of data and revised the manuscript. All authors approved the final manuscript.
Funding This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under award number R01DK105948 (the content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health), the Swedish “Reumatikerförbundet” (R-566571), the Swedish Research Council (K2013-54X-11285-19) and the Swedish federal government under LUA/ALF agreement concerning research and education of doctors.
Competing interests All authors have completed the Unified Competing Interests form at http://www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that LC has relationships with Astra Zeneca, MSD and Johnson and Johnson outside the submitted work in the previous 3 years; MN reports grants from Pfizer and Astra Zeneca and relationships with Roche and Itrim outside the submitted work in the previous 3 years; AR reports that part of the salary for her university full professor position at The Sahlgrenska Academy at the University of Gothenburg is covered by a grant from AstraZeneca IMed RIA (Respiratory, Inflammation, Autoimmunity) in compensation for advice regarding basic research in inflammation at the company; however, AR is not involved in any work regarding development of new treatments for gout.
Ethics approval Seven local ethics review boards approved the SOS study protocol.
Provenance and peer review Not commissioned; externally peer reviewed.